Carboxymethylation Of Cellulose Research Articles

Synthesis of cellulose modified material from waste straw and the growth-promotion effects on wheat

This study aimed to synthesize the cellulose-modified material [potassium carboxymethylcellulose (CMC-K)] based on wheat straw from straw cellulose by alkalization and etherification so as to enhance the use of waste straw and improve water and fertilizer efficiency. Potassium was introduced through the carboxymethylation of cellulose to supply nutrients to crops. Moreover, the order of influential factors on the water absorption property was determined by an orthogonal experiment. The results showed that the highest water absorbency of 196.2 g/g was achieved for the conditions of 1.5:1 potassium hydroxide to cellulose, 1.5:1 chloroacetic acid to cellulose, 50% potassium hydroxide, and 80% chloroacetic acid. The CMC-K was characterized by Fourier-transform infrared, x-ray diffraction, and scanning electron microscopy techniques, and the results indicated that the product exhibited excellent water-retention ability in the soil and reduced infiltration. The agricultural application of CMC-K promoted the growth indexes of wheat, which improved wheat yields. Moreover, it also increased total nitrogen, ammonium nitrogen, total potassium, and available potassium. The fertilizer efficiency and water-retention behavior of CMC-K encouraged its use as a safe water- and fertilizer-retaining agent and as a soil conditioner in agricultural applications.

Regeneration and carboxymethylation of cellulose and its derivatives: application assessment for brewery wastewater treatment

Coagulation–flocculation technique is usually employed in wastewater treatment by applying conventional inorganic materials such as alum and ferric chloride. Due cost to environmental challenges associated with the use of inorganic flocculants, biopolymers are gaining ground as alternative water treatment materials. In the present study, native cellulose and hemicelluloses isolated from sugarcane bagasse were used in the removal of turbidity and biological oxygen demand from industrial wastewater. Isolated native cellulose was modified to form regenerated cellulose (RC). Also, native cellulose, hemicellulose and RC were carboxymethylated using Na-chloroacetate. Thereafter, the functional groups on the carboxymethylated biopolymers were examined using Fourier transform infrared spectroscopy and the carbon–hydrogen–nitrogen–sulfur–oxygen elemental analysis. The degree of substitution (DS) for regenerated and carboxymethylated cellulosic materials was measured using recommended standard methods. Carboxymethyl cellulose (CMC) with 1.3 DS reduced turbidity and biological oxygen demand by 62.2 and 64%, respectively. Carboxymethyl regenerated cellulose (CMC-II) at 1.1 DS reduced turbidity and by 55.6 and 60%, respectively. Carboxymethyl hemicellulose (CMH) with 1.4 DS was capable of reducing turbidity and biological oxygen demand by 45.7 and 47%, respectively. Carboxymethyl cellulose and hemicellulose have rarely been used in the treatment of brewery wastewater. In the present study, these two novel materials showed a good prospect in removing biological oxygen demand and turbidity.

Cellulose-based polymer electrolyte derived from waste coconut husk: residual lignin as a natural plasticizer

Cellulose was isolated from waste coconut husk (Cocos nucifera) via alkali and single bleaching treatment. The isolated cellulose (CH-A-1B) was found to have residual lignin which imparts amorphous character to the polymer matrix as confirmed by X-ray diffraction analysis (XRD). Fourier transform infrared (FTIR) peak at 1507 cm−1 confirmed the presence of lignin and the appearance of three new peaks at 1320, 1416, and 1595 cm−1 showed successful attachment of carboxymethyl group onto the cellulose backbone. Carboxymethylation of cellulose from CH-A-1B produced carboxymethyl cellulose (CMC) with lower crystallinity compared to that of the double bleaching treatment cellulose (CH-A-2B). The CMC film prepared by solvent-casting method from CH-A-1B using 38 wt% NaOH possessed the highest conductivity of σ = 4.82 × 10−4 mS cm−1. The electrochemical properties of the CMC polymer electrolyte and the degree of crystallinity of the polymer matrix were found to be influenced by the amount of lignin content which acts as a natural plasticizer.

Thermal behavior of carboxymethyl cellulose in the presence of polycarboxylic acid crosslinkers

Cellulose is the most abundant biopolymer and with different chemical modification products yields excellent properties like high viscosity, hydrophilicity, defoaming, chelating ability, etc. Carboxymethyl cellulose (CMC) is a product of carboxymethylation of cellulose being extensively used in food industry, agriculture, wastewater treatment, pharmacy and medicine. Despite, carboxymethylation lowers the thermal stability of the cellulose. This study focuses on investigating the thermal stability of CMC by crosslinking with polycarboxylic acids such as citric acid and fumaric acid. The crosslinking occurs between the hydroxyl groups of CMC and carboxylic groups of polycarboxylic acids via esterification, as confirmed by the presence of ester bands in FTIR spectra. The decarboxylation temperature of CMC is increased from 548 to 573 K in the crosslinked samples. The glass and crystalline phase transitions of CMC shifted to higher temperatures with the addition of crosslinkers. This suggests that the thermal stability of the CMC can be increased with crosslinking agents maintaining the properties of cellulose which would extend the application of CMC in various other fields.

Synthesis and grafting of carboxymethyl cellulose from environmental pollutant cellulosic wastes of textile industry

Purpose This study aims to explore the use of knitted rag by synthesizing different grades of carboxymethyl cellulose (CMC) by applying multiple-step carboxymethylation techniques. Design/methodology/approach CMC was synthesized from knitted rag, a cellulosic waste of textile and garment industries, in aqueous ethanolic sodium hydroxide and subsequently mono-chloroacetic acid reaction medium. Low-substituted to high-substituted products were obtained from single-step to seven-step carboxymethylation of cellulose. In this way, it was possible to produce low-cost and different grades of substituted carboxymethylated cellulose. The synthesized CMC was characterized, and their physical properties were investigated. The structure of CMC and grafted CMC were investigated by Fourier transform infrared spectroscopy. Findings Solubility, CMC content, degree of substitution and molecular weight of CMC were increased gradually with the increase in the number of reaction steps, although fourth step attained the optimum. The cellulosic waste of knitted rag can easily be used to produce value-added products such as CMC and other cellulose derivatives, and that will ultimately reduce the pollution problems from this waste. Originality/value Grafting of prepared CMC film with methyl methacrylate monomer increased their strength, although decreased rigidity and moisture content because the incorporation of hydrophobic methyl methacrylate monomer was observed.

2,3,6-Tricarboxylate Cellulose as a Fully Biodegradable Flocculant: Efficient Synthesis and Flocculation Performance

Cellulose-based flocculants have shown excellent performance for wastewater flocculation, being low-cost and eco-friendly. However, they are still disturbed by the problems of incomplete biodegradability and unstable chemical structure. In the present study, 2,3,6-tricarboxylate cellulose (TCC) was developed as a novel fully biodegradable flocculant to deal with the preceding problems. The key carboxymethylation of cellulose was first carried out to make the subsequent NaIO4 oxidation occur under homogeneous conditions, which greatly enhanced the carboxylate content of the final TCC products. The chemical structure and solution properties of the TCCs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer system (XRD), field emission scanning electron microscopy (FESEM), charge density, particle size, and zeta potential. The flocculation performance of the TCCs was evaluated preliminarily by the turbidity removal of kaolin suspension. The positive results showed that all the TCC products had high carboxylate contents (more than 10 mmol/g) and zeta potentials. They exhibited excellent flocculation performance for the kaolin suspensions, in which the residual turbidities decreased from 610 to 14.9 NTU. Considering the degradation of cellulose caused by excessive NaIO4 oxidation, the TCC IV, together with its synthesis technology, could be used for practical applications in wastewater flocculation.

Microwave-assisted carboxymethylation of cellulose extracted from brewer's spent grain

Cellulose was extracted from brewer's spent grain (BSG) by alkaline and bleaching treatments. The extracted cellulose was used in the preparation of carboxymethyl cellulose (CMC) by reaction with monochloroacetic acid in alkaline medium with the use of a microwave reactor. A full-factorial 23 central composite design was applied in order to evaluate how parameters of carboxymethylation process such as reaction time, amount of monochloroacetic acid and reaction temperature affect the average degree of substitution (DS¯) of the cellulose derivative. An optimization strategy based on response surface methodology has been used for this process. The optimized conditions to yield CMC with the highest DS¯ of 1.46 follow: 5g of monochloroacetic acid per gram of cellulose, reaction time of 7.5min and temperature of 70°C. This work demonstrated the feasibility of a fast and efficient microwave-assisted method to synthesize carboxymethyl cellulose from cellulose isolated of brewer's spent grain.

Carboxymethylcellulose from recycled newspaper in aqueous medium

Recycled paper cellulose has some drawbacks, for example loss in mechanical strength, to use in paper industry alone. However, derivatives of cellulose can find applications in other industrial areas. Carboxymethylcellulose (CMC) is one of the most used cellulose derivatives and can be obtained by heterogeneous modification of cellulose. In general carboxymethylation of cellulose achieved in alkaline alcoholic dispersions. In this work modification of cellulose from recycled newspaper in aqueous alkaline solution was aimed. First cellulose was recovered from newspaper under oxidative alkaline conditions. Cellulose recovery was determined as 75–90% (w/w) of starting material. Carboxymethylation reactions were carried out to find optimum conditions for derivatization, changing concentrations of components and reaction temperature. Obtained CMC samples had a DS of 0.3–0.7% and 84–94% CMC content. As a result, carboxymethylation of cellulose from recycled newspaper was achieved in aqueous alkaline dispersion giving commercial grade CMC for industrial use.

Utilization of cellulosic wastes in textile and garment industries. I. Synthesis and grafting characterization of carboxymethyl cellulose from knitted rag

AbstractCarboxymethyl cellulose (CMC) was synthesized from knitted rags, a cellulosic wastes of textile and garment industries, in aqueous ethanolic sodium hydroxide and subsequently mono‐chloroacetic acid reaction medium. A low substituted to high substituted products was obtained from single step up to seven steps carboxymethylation of cellulose. In this way, it was possible to produce low cost and different grades or substituted carboxymethylation derivatives of cellulose. Solubility, degree of substitution (DS), CMC content, and molecular weight of CMC were increased gradually with the increase of the number of reaction steps, although fourth step attained optimal. The DS of CMC from one to seven reaction steps was 0.91–2.84, respectively. Similarly, CMC content and molecular weight of CMC were 72.60%–85.00% and 153,886–252,231, respectively. Grafting of CMC film with methyl methacrylate (MMA) improved strength properties, but it decreased moisture content due to the incorporation of hydrophobic MMA monomer. The prepared CMC, when applied as sizing agent to cotton fabric, was deposited on the fabric surface through bond formation making it smooth without any crack or rupture. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Carboxymethylation of cellulose using reactive extrusion

Carboxymethyl cellulose was prepared using a continuous, reduced solvent, reactive extrusion process with a short reaction time. The effects of the amounts of NaOH (30 g, 40 g and 50 g), water:ethanol ratio (100%, 70%, 50%, 30% and 10% H2O) and their interactions on the physical, chemical and morphological properties of carboxymethyl cellulose were studied. Experiments were conducted using to a 5 × 3 blocked factorial design. X-ray diffraction analyses revealed higher degrees of crystallinity and fractions of cellulose-II crystalline structure when 100% H2O was used as compared to that for 70%, 50%, 30% and 10% H2O and a commercially available brand of carboxymethyl cellulose, AQUASORB A500. Statistical analysis revealed a significant interaction between the effects of NaOH and H2O on the degrees of substitutions. The degrees of substitutions decreased with increasing amounts of NaOH and tended to increase with increasing alcohol concentrations. Liquid uptake measurements revealed that the extent of saline uptake, measured at intervals of 1 min, 5 min and 10 min, by carboxymethyl cellulose prepared with 100% H2O, especially when 40 g and 50 g NaOH was used, was higher than that for 70%, 50%, 30% and 10% H2O and AQUASORB A500. This may have been because of the higher crystallinity in carboxymethyl cellulose prepared with 100% H2O. Carboxymethyl cellulose prepared with 70% H2O and 30 g and 50 g NaOH had the highest saline absorption, using the soak method, before and after centrifugation, respectively. Scanning electron microscopy for carboxymethyl cellulose prepared with 100% and 10% H2O, through images at 120X magnification, revealed fibers 100 μ to >800 μ in length and 0.8–3.3 μ in breadth. Some non fibrous particles, 0.8–6.7 μ in dimensions, also were observed for 100% H2O. Images at 900× magnification revealed partially damaged fiber surfaces.

A chemical engineering approach to cellulose substitution kinetics

A general kinetic model for the substitution of cellulose was developed. The model assesses the differences in the reactivity of the cellulose hydroxyl groups and a decrease in the reactivity as the substitution proceeds. The model predicts the detailed distribution of the different mono (2, 3, 6)-, di (23, 26, 36) – and trisubstituted (236) units as a function of the reaction time. The classical Spurlin distribution is obtained as a special case of the general model. Numerical strategies were developed for the solution and computer simulation of the model. Simulation results were shown to be valid for various reactivity ratios of the hydroxyl groups. The modelling concept was verified with experimental data obtained for carboxymethylation of cellulose in a slurry reactor. The detailed data, which revealed the non-uniform reactivities of the different hydroxyl groups and the decline of the substitution rate with time, were successfully described by the mathematical model.

Modelling and experimental verification of cellulose substitution kinetics

Cellulose and starch derivatives are often prepared by substitution reactions to the hydroxyl groups (OH-2, OH-3 and OH-6) of the corresponding anhydroglucose units. A general kinetic model for the substitution of cellulose and starch was developed. The model assumes different reactivities of the hydroxyl groups and a decrease in the reactivity as the substitution proceeds. Both phenomena are taken into account in the model. The model predicts the detailed distribution of the different mono (2, 3, 6)-, di (23, 26, 36)—and trisubstituted (236) units as a function of the reaction time. The classical Spurlin distribution is obtained as a special case of the general model. Numerical strategies were developed for the solution and computer simulation of the model. Simulation results were shown to be valid for various reactivity ratios of the hydroxyl groups. The modelling concept was verified with experimental data obtained for carboxymethylation of cellulose. It should be emphasized, however, that the same general approach is also applicable in studies of any hemicelluloses or oligo- or monosaccharides. The detailed data, which revealed the non-uniform reactivities of the different hydroxyl groups and the decline of the substitution rate with time, were successfully described by the mathematical model.

Homogenous Carboxymethylation of Cellulose in the New Alkaline Solvent LiOH/Urea Aqueous Solution

AbstractIn this work, the carboxymethylation of cellulose in a new alkaline cellulose solvent, LiOH/urea aqueous solution, was investigated. Carboxymethyl cellulose (CMC) samples were characterized with FT‐IR, NMR, HPLC, and viscosity measurements. Water‐soluble CMC with DS = 0.36∼0.65 was prepared, from both Avicel cellulose and cotton linters in the LiOH/urea system. The total DS of CMC could be controlled by varying the molar ratio of reagents and the reaction temperature. The results from structure analysis by HPLC after complete depolymerization showed that the mole fractions of the different carboxymethylated repeating units as well as those of unmodified glucose follow a simple statistic pattern. A distribution of the carboxymethyl groups of the AGU was determined to be in the order O‐6 > O‐2 > O‐3 position at the level.

Evaluation of molten inorganic salt hydrates as reaction medium for the esterification of cellulose

Molten inorganic salt hydrates are highly efficient solvents forcellulose. The carboxymethylation of the polymer dissolved in this new group ofcellulose solvents was investigated. The homogeneous carboxymethylation ofcellulose in molten LiClO4•3H2O using sodiummonochloroacetate in the presence of NaOH is possible. The formation of CMC wasconfirmed by FT- Raman spectroscopy. Structure analysis by means of HPLC afterchain degradation showed the formation of CMC with a DS of 2 after a shortreaction time of 4 h. The derivatives exhibit a statisticaldistribution of substituents along the polymer chain if prepared in moltenLiClO4•3H2O as solvent. A substituent distributioninthe order C-6 > C-2 ≈ C-3 for anhydroglucose units (AGU) was concludedfrom 1H-NMR measurements. The synthesis of CMC in the swellingmediumLiCl•xH2O (2 ≤ x ≤ 5) yields polymers with astatistical distribution of functional groups along the chain. The watercontentof the salt melts has a dramatic influence on the DSCMC.

Homogenous carboxymethylation of cellulose in the NaOH/urea aqueous solution

In this work, the carboxymethylation of cellulose in the alkaline cellulose solvent, 7 wt% NaOH/12 wt% urea aqueous solution, was investigated. Carboxymethyl cellulose (CMC) samples were characterized with FT-IR, NMR, HPLC, and viscosity measurements. Water-soluble CMC with DS = 0.20–0.62 was prepared from both Avicel cellulose and cotton linters. Thus, carboxymethylation of cellulose in NaOH/urea leads to a polymer with the lowest DS value for water solubility (0.20) of CMC known. The total DS of CMC could be controlled by varying the molar ratio of reagents and NaOH to AGU and the reaction temperature. Structure analysis by means of HPLC after complete depolymerization showed that the mole fractions of the different carboxymethylated repeating units as well as those of unmodified glucose follow the simple statistic pattern. A distribution of the carboxymethyl groups at the level of the AGU in the order O-6 > O-2 > O-3 was determined. The results were similar with findings for CMC obtained by totally homogeneous reaction of cellulose in aqueous solvents such as Ni[tris(2-aminoethyl)amine](OH) 2.

Experimental study on carboxymethylation of cellulose extracted from Posidonia oceanica

AbstractThe production of carboxymethylcellulose (CMC) from bleached cellulose pulps obtained from Posidonia oceanica was explored. The optimal reaction conditions were studied for the carboxymethylation of cellulose in organic liquids. The carboxymethylation reaction was carried out with NaOH and monochloroacetic acid (MAC) as the reagent. Different alcohols were compared in terms of the degree of substitution (DS). The highest DS was obtained with n‐butanol. For this alcohol, the effects of the temperature, alkali concentration, and MAC concentration were studied. The reaction was also carried out in three consecutive steps. The resulting CMC had a DS of about 2.75. The functionalization of cellulose was checked using FTIR spectroscopy and 13C‐NMR. The X‐ray analysis showed that the crystalline structure of cellulose decreased when the DS increased and the structure was totally amorphous in high DS material. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1808–1816, 2006

Distribution of carboxyl groups in carboxymethylated cotton fibers

Cotton cellulose was partially carboxymethylated by a one-bath method using monochloroacetic acid and sodium hydroxide. A method was developed to study the extent of the carboxymethylation of cellulose within the cotton fibers using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Uranyl nitrate was used as a stain. Scanning electron photomicrographs revealed that the carboxymethylation of cellulose occurred throughout the cotton fiber cross section. However, the X-ray microanalysis data indicated a variation in the extent of the reaction among the morphological regions that have different chemical accessibility. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 203–207, 1999

Carboxymethylation of cellulose in unconventional media

Carboxymethylation of cellulose in the new and highly efficient aqueous solvent Ni(tren)(OH)2 (trenDtris(2-aminoethyl)amine) and in melts of LiClO4 3H2 Oo rN-methyl- morpholine-N -oxide (NMMNO), which is now widely applied for cellulose fibre production, was investigated. In case of Ni(tren)(OH)2, a totally homogeneous carboxymethylation of cellulose with sodium monochloroacetate, in the presence of an aqueous NaOH solution is possible for the first time. Structure analysis by means of HPLC and 1 H-NMR after chain degradation showed results comparable with findings for CMC obtained by the heterogeneous slurry process, that is, a statistic distribution of substituents along the polymer chain and functionalisation of the hydroxyl groups in the order C-6 C-2> C-3. The etherification of cellulose in a melt of LiClO43H2O, a new type of cellulose solvent, was shown to be possible and gave products of a statistic functionalisation pattern as well. In contrast, carboxymethyla- tion starting from solutions of cellulose in NMMNO initiated with solid NaOH particles yields polymers with a nonstatistic distribution of functional groups along the chain, as observed for cellulose ethers prepared in reactive microstrctures starting from solutions of cellulose inter- mediates in dimethyl sulfoxide as well as of unmodified cellulose dissolved in N,N-dimethyl acetamide/LiCl.

Synthesis path versus distribution of functional groups in cellulose ethers

AbstractDifferent ways for carboxymethylation of cellulose are discussed exemplary for cellulose ether synthesis in terms of the resulting structural features. The industrially applied slurry process yields polymers with statistic amounts of the four differently substituted repeating units glucose, mono‐, di‐, and tri‐O‐carboxymethylglucose. Surprisingly, the newly developed totally homogeneous carboxymethylation in the efficient cellulose solvent Ni[tris(2‐aminoethyl)amine](OH)2 gives exactly the same result. Thus, the polymer is evenly accessible during both reaction paths. In contrast the carboxymethylation starting from homogeneous solutions of cellulose in N,N‐dimethyl acetamide /LiCl or solutions of reactive derivatives of cellulose in dimethyl sulfoxide (DMSO) yields polyelectrolytes with a nonstatistic content of the building units. This is achieved via an induced phase separation forming highly reactive microstructures.

Kinetic study of the carboxymethylation of cellulose

The kinetics of carboxymethylation of mercerized Na-cellulose was studied in a laboratory-scale batch reactor operating at atmospheric pressure and at temperatures in the range 30--80 C. Based on the experimental data a bimolecular kinetic model for carboxymethylation was developed. The model takes into account the decline of the intrinsic activities of the hydroxyl groups of cellulose as the substitution proceeds. The parameters of the kinetic model were determined by regression analysis, and the model described well the experimentally determined carboxymethylation kinetics. The distribution of mono-, di-, and trisubstituted anhydroglucose units in (carboxymethyl) cellulose was simulated using the parameters of the kinetic model.